MartyniP.co.uk

flags.martynip.co.uk is a archive of world wide flags compiling of 270 flags for most countries,
and a few special flags such as Isle of Man, EU and NATO flags.

You may use this feature for any needs, flag sizes are 18x12px, flags are named as (countrycode).png (eg, http://flags.martynip.co.uk/gb.png ) in lower case.
Upper case country codes will return the white box with a black border.

Works well with Maxmind GeoIP country codes, few flags are missing though.